This is an exploratory multi PI proposal that will merge the unique expertise of two investigators from two different disciplines to apply an innovative approach to address an unmet need, namely, that there are no FDA approved drugs for the prevention and treatment of acute kidney injury (AKI). Low statistical power, poorly timed administration of the drug, and adverse effects have hampered the success of clinical trials. We propose a new approach in the field of AKI using ultrasound (US)-stimulated drug delivery from drug-loaded nanoparticles. Although nanoparticles (liposomes) have already been approved and are in use for cancer therapy, our studies incorporate recent advances in the field of nanotechnology yet to be tested in targeted drug delivery. Current delivery systems use microbubbles that consist of a gas core encapsulated by a shell (several nm thick) with drugs embedded within the membrane or attached to the surface, or drug-loaded liposomes that decorate the surface of microbubbles. During insonation, microbubbles oscillate; higher US intensities destroy the microbubbles, partially releasing the liposome payload. The disadvantage of this drug carrier system is its short circulation time (gas is usually lost from the bubble within minutes following intravenous administration) and incomplete drug release. Furthermore, the large size of the complex (micrometers) limits extravasation of the particles beyond the vascular bed. We propose to develop a novel drug carrier system (shiftosome) that is based on the combination of two carrier approaches, i.e. liposome nanoparticles loaded with phase-shift nanoparticle agents. These studies will use a superheated liquid perfluorocarbon (e.g. perfluoropentane and/or perfluorobutane) filled nanoparticle inside the liposome internal core along with the entrapped drug. We will test the hypothesis that shiftosomes have improved characteristics and can specifically target a novel sphingosine 1 receptor (S1P1) analog to the kidney endothelium to reduce kidney ischemia-reperfusion injury (IRI). Specific Aim 1 will test the hypothesis that the novel drug carrier system, shiftosome, has improved characteristics for ultrasound-triggered drug delivery, and, when loaded with FTY720, can reduce vascular endothelial or tubular epithelial injury in vitro. Specific Aim 2 will test the hypothesis that the S1P agonist, FTY720, carried by the novel drug carrier system is targeted selectively to the kidney to reduce kidney IRI in vivo. At the end of two years, we will have identified: 1) if shiftosomes are safe, effective and selective in targeting to the kidney, and 2) if FTY720, a leading candidate for clinical trials in AKI, can be selectively delivered to the kidney to avoid potential systemic side effects. These studies will provide the foundation for future preclinical studies using a novel carrier approach to treat AKI.